Influence of organic waste amendments on uptake of per and polyfluoroalkyl substances from soil to crops: Insights from long-term field experiments

The use of organic waste products (OWPs) as soil amendments raises concerns due to the potential uptake and accumulation of several environmental contaminants, such as per- and polyfluoroalkyl substances (PFAS) in plants. We developed an analytical procedure suitable for screening 75 anionic, zwitterionic, and cationic PFAS in plant tissues (limits of detection: 0.01-0.7 μg/kg). PFAS recoveries were verified in diverse types of crops representative of French agriculture, including maize and wheat (Mainland France) and sugarcane (Overseas France). In the second step, we applied this method to investigate PFAS uptake and accumulation in maize, wheat, and sugarcane grown in experimental fields of France. The ∑₇₅ PFAS in crops harvested from these sites remained relatively low (0.01-2.5 μg/kg) without effects of OWP amendments on plant PFAS concentrations, despite an increase in PFAS in OWP-amended soils. A negative correlation between soil organic carbon and ∑₇₅ PFAS in plants suggests a possible inhibition of PFAS uptake by crops as soil organic matter increases. The dominant PFAS in plant samples included perfluorobutanoic acid (PFBA: 0.10-2.2 μg/kg), perfluorooctanoic acid (PFOA: 0.02-0.66 μg/kg), and perfluorooctane sulfonate (PFOS: 0.01-0.48 μg/kg), accounting for 64-80 % (PFBA), 14-16 % (PFOA) and 6-13 % (PFOS) of the total PFAS, with bioaccumulation factors higher than unity for PFBA and lower than unity for PFOS and PFOA. Bioaccumulation factors were significantly higher in young leaves than in grains, implying limited PFAS transfer to the edible plant tissues of maize and wheat. With the recent lower reference doses (RfD) recommended by the USEPA (2021-2024), the consumption of grains in this study can pose significant risks to humans; however, considering the RfD from EFSA, these crops are safe for human consumption.